Yanmar 4JH5E Engine Review

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Are you ready for a powerful, naturally-aspirated recreational marine diesel engine? We thought so. The Yanmar 4JH5E is all that and so much more. A stellar example of direct injection diesel that is as clean for the environment as its indirect competitors.

Not only does the new diesel engine generate more torque, but crucially it also complies with the European and United States exhaust emission regulations. Courtesy of redesigned piston crowns and combustion chambers, it is now possible for avid boaters to own an engine that delivers the best of both worlds – greater power and less harmful emissions.

If you’re in the market for a reliable engine with powerful fuel efficiency for your recreational needs, then the Yanmar 4JH5E might just be the right choice for you.

Why Yanmar?

For the sailing obsessed and regular commercial shippers, Yanmar is a trusted name in engine manufacturing. For over 83 years, since producing the very first commercially viable small diesel engine, consumers have relied on Yanmar engines to safely sail around the world.

Yanmar is dedicated to designing engines that produce clean emissions and are low in noise and vibration. The company as a whole is committed to providing machines that use energy with the utmost efficiency, raising agricultural and industrial productivity. And the Yanmar 4JH5E is no exception.

The Demand

Better fuel efficiency is one of the most important deliveries boat owners will look for in an engine. Of course, this will change depending on the model of your boat and purpose for your travel. A leisurely cruise around the bay will meet different criteria when compared to high-speed motoring.

In recent years, direct injection diesel engines have overtaken indirect-injections hugely in popularity.  This can be attributed in part to the ease of not having to handle pre-combustion chambers, which ignite fuel before reaching the combustion chamber. This practice, often incorporated in older direct-injection diesels, means that the fuel is never burnt completely and high exhaust emissions are released.

So what do boat owners really need in their engine? Durability, power, better sustainability and complete accessibility when it comes to repairs. So, does the Yanmar 4JH5E tick all the boxes?

The Model

For commercial shippers and sailing enthusiasts, Yanmar is an obvious choice. A trusted name in engine manufacturing since 1933, consumers rely on Yanmar to deliver engines designed to maximise power, minimise noise and vibration, and produce clean emissions.

The Yanmar 4JH5E marine diesel engine certainly delivers, as a four-cylinder version of the three-cylinder 3JH5E. While the extra pot does increase the gearbox weight by 15%, it is understandably countered by the rise in power, a staggering 38% increase.

A standard carry on for Yanmar marine engines is the heat exchanger cooling, an 80-amp-voltage-regulated alternator found on this latest version. While it may be a little light for an engine of this output, the choice is there for additional alternators should you prefer.

For boat owners with curious fingers, a shroud is even included over the drive belt for the fresh water circulating pump and alternator.

Perhaps one of the best advantages of this engine design is that it’s well-suited to run Yanmar’s mechanical cone clutch gearbox, with different angle outputs. This has a greater gear reduction when in reverse, which reduces engine loading and allows the torque band to be reached quicker.

The Verdict?

It is Yanmar’s unique understanding of what boat owners not only want, but really need, in an engine that is a real point of difference in the recreational marine diesel manufacturing market. The ideal engine is one that you can rely on no matter what happens – to not only get the job done, but do it right.

The Yanmar 4JH5E diesel engine is designed to use energy with the utmost efficiency, a reflection of the changing attitudes in sustainability. Low fuel consumption is really a large part of the total package, which offers a substantially lighter alternative for boat owners. Plus, in meeting the regulations for exhaust emissions, you can boat safe in the knowledge that billows of smoke won’t be blowing around your transom.

If you want to know more about this diesel engine, including all the specs we know you live for, read the full review of the Yanmar 4JH5E at Trade-A-Boat’s.